1. Field of the Invention
The present invention relates to an actuator module reduced in weight and capable of causing deformation such as expansion and contraction, bending, or the like repetitively by electric signals, and a material used therefor.
2. Description of the Related Art
Medical or nursing fields require safety actuators that can be micro-miniaturized and reduced in weight and that are flexible and operated at a low driving voltage for the application use of active catheters, endoscopes, rehabilitation aids, powered suits, artificial organs, etc. Further, paper displays and portable haptic devices for which a new demand will be expected in the future require actuators capable of attaining complicate movements in a small space in addition to the properties described above. As described above, not only actuators that can generate large stresses and high-speed response and can be controlled with high accuracy as usual but also actuators that can be micro-miniaturized and reduced in weight, and that is flexible and safe attaching to the boty (low driving voltage) will be necessary in the future.
For the actuators that can be micro-miniaturized, actuators in which a material per se can deform repetitively by electric signals are more suitable than those requiring assembling of parts such as an electromagnetic motor used usually. Actuators well-known at present in which the material per se deforms repetitively include a piezo actuator utilizing the piezo effect of ferroelectrics and an SMA actuator utilizing the phase transition of a shape-memory alloy (SMA). However, they have good and bad points in view of the driving voltage, the weight, and the durability.
As the actuator using the material that is deformed by electric signals, several kinds of actuators utilizing organic materials that deform by electric signals have been proposed in recent years, separately from the existent actuators described above. Since such actuators use organic materials, they have an advantage of reduced weight. They include, specifically, polymer actuators represented typically, for example, by a conductive polymer actuator using a conductive polymer such as polyaniline or polypyrrole for the material (Patent Document 1: JP-A No. 02-20586), an ionically conductive polymer actuator using an ionically conducting polymer as the material (Patent Document 2: JP-A No. 06-6991), a fine conductive particles mixed ionic polymer actuator in which fine conductive particles are bound with an ionic conductive polymer (Non-Patent Document 1: “Expanding actuator using ionic conductive polymer, by Masayoshi Ishibashi, Midori Kato, in 53th Annual Meeting of the Society of Polymer Science, Japan, 2004, IPA155), an actuator utilizing thermal deformation upon molecular desorption of conductive polymer (Patent Document 3: JP No. 3131180) and an actuator of using a material formed by mixing fine conductive particles to a shape memory resin (Patent Document 4: JP-A No. 02-242847, Patent Document 5: JP-A No. 02-155955).